[clangd] Improve document symbols support for Objective-C categories and methods

- Categories will now show up as `MyClass(Category)` instead of
  `Category` and `MyCategory()` instead of `(anonymous)` in document
  symbols

- Methods will now be shown as `-selector:` or `+selector:`
  instead of `selector:` to differentiate between instance and class
  methods in document symbols

Differential Revision: https://reviews.llvm.org/D96612

clang-tools-extra/clangd/FindSymbols.cpp

@@ -172,6 +172,26 @@ getWorkspaceSymbols(llvm::StringRef Query, int Limit,
 }
 
 namespace {
+std::string getSymbolName(ASTContext &Ctx, const NamedDecl &ND) {
+  // Print `MyClass(Category)` instead of `Category` and `MyClass()` instead
+  // of `anonymous`.
+  if (const auto *Container = dyn_cast<ObjCContainerDecl>(&ND))
+    return printObjCContainer(*Container);
+  // Differentiate between class and instance methods: print `-foo` instead of
+  // `foo` and `+sharedInstance` instead of `sharedInstance`.
+  if (const auto *Method = dyn_cast<ObjCMethodDecl>(&ND)) {
+    std::string Name;
+    llvm::raw_string_ostream OS(Name);
+
+    OS << (Method->isInstanceMethod() ? '-' : '+');
+    Method->getSelector().print(OS);
+
+    OS.flush();
+    return Name;
+  }
+  return printName(Ctx, ND);
+}
+
 std::string getSymbolDetail(ASTContext &Ctx, const NamedDecl &ND) {
   PrintingPolicy P(Ctx.getPrintingPolicy());
   P.SuppressScope = true;
@@ -220,7 +240,7 @@ llvm::Optional<DocumentSymbol> declToSym(ASTContext &Ctx, const NamedDecl &ND) {
   SymbolKind SK = indexSymbolKindToSymbolKind(SymInfo.Kind);
 
   DocumentSymbol SI;
-  SI.name = printName(Ctx, ND);
+  SI.name = getSymbolName(Ctx, ND);
   SI.kind = SK;
   SI.deprecated = ND.isDeprecated();
   SI.range = Range{sourceLocToPosition(SM, SymbolRange->getBegin()),

clang-tools-extra/clangd/unittests/FindSymbolsTests.cpp

@@ -912,6 +912,42 @@ TEST(DocumentSymbolsTest, DependentType) {
                     WithDetail("<dependent type>"))))));
 }
 
+TEST(DocumentSymbolsTest, ObjCCategoriesAndClassExtensions) {
+  TestTU TU;
+  TU.ExtraArgs = {"-xobjective-c++", "-Wno-objc-root-class"};
+  Annotations Main(R"cpp(
+      $Cat[[@interface Cat
+      + (id)sharedCat;
+      @end]]
+      $SneakyCat[[@interface Cat (Sneaky)
+      - (id)sneak:(id)behavior;
+      @end]]
+
+      $MeowCat[[@interface Cat ()
+      - (void)meow;
+      @end]]
+      $PurCat[[@interface Cat ()
+      - (void)pur;
+      @end]]
+    )cpp");
+  TU.Code = Main.code().str();
+  EXPECT_THAT(
+      getSymbols(TU.build()),
+      ElementsAre(
+          AllOf(WithName("Cat"), SymRange(Main.range("Cat")),
+                Children(AllOf(WithName("+sharedCat"),
+                               WithKind(SymbolKind::Method)))),
+          AllOf(WithName("Cat(Sneaky)"), SymRange(Main.range("SneakyCat")),
+                Children(
+                    AllOf(WithName("-sneak:"), WithKind(SymbolKind::Method)))),
+          AllOf(
+              WithName("Cat()"), SymRange(Main.range("MeowCat")),
+              Children(AllOf(WithName("-meow"), WithKind(SymbolKind::Method)))),
+          AllOf(WithName("Cat()"), SymRange(Main.range("PurCat")),
+                Children(
+                    AllOf(WithName("-pur"), WithKind(SymbolKind::Method))))));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang